>I can sort of see where this would be useful. Lets say a customer
>comes into a dealership, is underwater in his current car but wants
>out of it and into something else.
>
>Take whatever the difference is between the trade value and still owed
>on the first car PLUS add in the new car = One 96 Month Loan

The odds are any decent bank won't carry that amount of negative
equity on that long a term. It doesn't make fiscal/risk sense to do
it unless the person has a fantastic credit score (say, 720+ beacon).

It still stands that if you can't afford a car with payments of 48
months or less, you can't afford that car.